Objective: To describe the clinical, biomarker, genetic and pathological features of a cohort of patients with corticobasal syndrome (CBS).

Background: Corticobasal degeneration (CBD) was first described as a pathological entity in 1967, linked to a late-onset progressive disorder involving asymmetrical rigidity and myoclonus. Armstrong et al. (2013) described 4 clinical phenotypes associated with this pathology, including CBS, through retrospective analysis of published cases and confirmed brain bank cases of CBD. Predicting CBD during the patients’ lifetime remains challenging. To date, no study has been conducted on a large cohort of CBS cases incorporating detailed prospective clinical data.

Method: PROSPECT-M-UK is a UK-based multicentre observational study which prospectively recruits patients with atypical parkinsonism. CLEAR is its sister project, recruiting CBS cases across Europe. The majority of patients in these studies have detailed interviews and neurological examinations, and undergo biomarker sampling and genetic testing. We have included pathologically-confirmed CBD cases to perform detailed analysis of clinical, biomarker and pathological data.

Results: A total of 394 (58% female) cases were included, of which 167 have detailed prospective clinical data, 148 have had cognitive assessments and 142 have autopsy data available. The median age at symptom onset was 68. In the prospective cohort, the mean time from symptom onset to recruitment was 4.48 years. Mean MDS-UPDRS and PSP-RS scores were 58.26 and 14.91, respectively. 80% scored ≤ 60% on the Schwab and England Activities of Daily Living Scale, indicating loss of functional independence. Of the included cases, 38 have biomarker/pathology defined CBS-AD and 163 have biomarker/pathology defined CBS-4RT. Initial comparisons between these groups have shown differences. Further analysis of genetic, clinical and biomarker features of these different diseases is ongoing to enable future biomarker driven clinical trials.

Conclusion: To our knowledge, this international collaboration is the largest prospective deep phenotyping study of CBS. Our prospective cohort had advanced disease at recruitment, highlighting issues with delay to diagnosis of CBS. Detailed analysis will characterise common clinical features, initial symptoms, MRI features, CSF biomarkers and genetic data. A subset also have autopsy data for analysis.

References: 1. Rebeiz JJ, Kolodny EH, Richardson EP (1967) Corticodentatonigral degeneration with neuronal achromasia: a progressive disorder of late adult life. Transactions of the American Neurological Association, 92,23—26.
2. Armstrong MJ, Litvan I, Lang AE, Bak TH, Bhatia KP, Borroni B, Boxer AL, Dickson DW, Grossman M, Hallett M, Josephs KA, Kertesz A, Lee SE, Miller BL, Reich SG, Riley DE, Tolosa E, Tröster AI, Vidailhet M, Weiner WJ. Criteria for the diagnosis of corticobasal degeneration. Neurology. 2013 Jan 29;80(5):496-503. doi: 10.1212/WNL.0b013e31827f0fd1. PMID: 23359374; PMCID: PMC3590050.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/describing-the-syndrome-a-comprehensive-analysis-of-a-large-cohort-of-corticobasal-syndrome-with-pathological-correlation/